private void MoveBranchNode(TreePage parentPage, TreePage from, TreePage to)
{
Debug.Assert(from.IsBranch);
Slice originalFromKey;
using (GetActualKey(from, from.LastSearchPositionOrLastEntry, out originalFromKey))
{
to.EnsureHasSpaceFor(_tx, originalFromKey, -1);
var fromNode = from.GetNode(from.LastSearchPosition);
long pageNum = fromNode->PageNumber;
if (to.LastSearchPosition == 0)
{
// cannot add to left implicit side, adjust by moving the left node
// to the right by one, then adding the new one as the left
TreeNodeHeader *actualKeyNode;
Slice implicitLeftKey;
using (GetActualKey(to, 0, out actualKeyNode, out implicitLeftKey))
{
var implicitLeftNode = to.GetNode(0);
var leftPageNumber = implicitLeftNode->PageNumber;
Slice implicitLeftKeyToInsert;
ByteStringContext.ExternalScope?externalScope;
if (implicitLeftNode == actualKeyNode)
{
externalScope = TreeNodeHeader.ToSlicePtr(_tx.Allocator, actualKeyNode, out implicitLeftKeyToInsert);
}
else
{
implicitLeftKeyToInsert = implicitLeftKey;
externalScope = null;
}
to.EnsureHasSpaceFor(_tx, implicitLeftKeyToInsert, -1);
to.AddPageRefNode(1, implicitLeftKeyToInsert, leftPageNumber);
externalScope?.Dispose();
to.ChangeImplicitRefPageNode(pageNum); // setup the new implicit node
}
}
else
{
to.AddPageRefNode(to.LastSearchPosition, originalFromKey, pageNum);
}
}
if (from.LastSearchPositionOrLastEntry == 0)
{
var rightPageNumber = from.GetNode(1)->PageNumber;
from.RemoveNode(0); // remove the original implicit node
from.ChangeImplicitRefPageNode(rightPageNumber); // setup the new implicit node
Debug.Assert(from.NumberOfEntries >= 2);
}
else
{
from.RemoveNode(from.LastSearchPositionOrLastEntry);
}
var pos = parentPage.LastSearchPositionOrLastEntry;
parentPage.RemoveNode(pos);
Slice newSeparatorKey;
var scope = GetActualKey(to, 0, out newSeparatorKey); // get the next smallest key it has now
try
{
var pageNumber = to.PageNumber;
if (parentPage.GetNode(0)->PageNumber == to.PageNumber)
{
pageNumber = from.PageNumber;
scope.Dispose();
scope = GetActualKey(from, 0, out newSeparatorKey);
}
AddSeparatorToParentPage(to, parentPage, pageNumber, newSeparatorKey, pos);
}
finally
{
scope.Dispose();
}
}
private void MoveLeafNode(TreePage parentPage, TreePage from, TreePage to)
{
Debug.Assert(from.IsBranch == false);
Slice originalFromKeyStart;
using (GetActualKey(from, from.LastSearchPositionOrLastEntry, out originalFromKeyStart))
{
var fromNode = from.GetNode(from.LastSearchPosition);
byte *val = @from.Base + @from.KeysOffsets[@from.LastSearchPosition] + Constants.Tree.NodeHeaderSize +
originalFromKeyStart.Size;
byte *dataPos;
var fromDataSize = fromNode->DataSize;
switch (fromNode->Flags)
{
case TreeNodeFlags.PageRef:
to.EnsureHasSpaceFor(_tx, originalFromKeyStart, -1);
dataPos = to.AddPageRefNode(to.LastSearchPosition, originalFromKeyStart, fromNode->PageNumber);
break;
case TreeNodeFlags.Data:
to.EnsureHasSpaceFor(_tx, originalFromKeyStart, fromDataSize);
dataPos = to.AddDataNode(to.LastSearchPosition, originalFromKeyStart, fromDataSize);
break;
case TreeNodeFlags.MultiValuePageRef:
to.EnsureHasSpaceFor(_tx, originalFromKeyStart, fromDataSize);
dataPos = to.AddMultiValueNode(to.LastSearchPosition, originalFromKeyStart, fromDataSize);
break;
default:
throw new NotSupportedException("Invalid node type to move: " + fromNode->Flags);
}
if (dataPos != null && fromDataSize > 0)
{
Memory.Copy(dataPos, val, fromDataSize);
}
from.RemoveNode(from.LastSearchPositionOrLastEntry);
var pos = parentPage.LastSearchPositionOrLastEntry;
parentPage.RemoveNode(pos);
Slice newSeparatorKey;
var scope = GetActualKey(to, 0, out newSeparatorKey); // get the next smallest key it has now
try
{
var pageNumber = to.PageNumber;
if (parentPage.GetNode(0)->PageNumber == to.PageNumber)
{
pageNumber = from.PageNumber;
scope.Dispose();
scope = GetActualKey(from, 0, out newSeparatorKey);
}
AddSeparatorToParentPage(to, parentPage, pageNumber, newSeparatorKey, pos);
}
finally
{
scope.Dispose();
}
}
}
private void AddSeparatorToParentPage(TreePage childPage, TreePage parentPage, long pageNumber, Slice seperatorKey, int separatorKeyPosition)
{
var parent = new ParentPageAction(parentPage, childPage, _tree, _cursor, _tx);
parent.AddSeparator(seperatorKey, pageNumber, separatorKeyPosition);
}
private static void ThrowOnCompressedPage(TreePage p)
{
throw new PageCompressedException($"Page {p} is compressed. You need to decompress it to be able to access its content.");
}
private bool TryUseRecentTransactionPage(Slice key, out TreeCursorConstructor cursor, out TreePage page, out TreeNodeHeader *node)
{
var foundPage = _recentlyFoundPages?.Find(key);
if (foundPage == null)
{
page = null;
node = null;
cursor = default(TreeCursorConstructor);
return(false);
}
var lastFoundPageNumber = foundPage.Number;
if (foundPage.Page != null)
{
// we can't share the same instance, Page instance may be modified by
// concurrently run iterators
page = new TreePage(foundPage.Page.Base, foundPage.Page.PageSize);
}
else
{
page = GetReadOnlyTreePage(lastFoundPageNumber);
}
if (page.IsLeaf == false)
{
VoronUnrecoverableErrorException.Raise(_llt.Environment, "Index points to a non leaf page");
}
node = page.Search(_llt, key); // will set the LastSearchPosition
cursor = new TreeCursorConstructor(_llt, this, page, foundPage.CursorPath, lastFoundPageNumber);
return(true);
}
private byte *SplitPageInHalf(TreePage rightPage)
{
bool toRight;
var currentIndex = _page.LastSearchPosition;
var splitIndex = _page.NumberOfEntries / 2;
if (currentIndex <= splitIndex)
{
toRight = false;
}
else
{
toRight = true;
var leftPageEntryCount = splitIndex;
var rightPageEntryCount = _page.NumberOfEntries - leftPageEntryCount + 1;
if (rightPageEntryCount > leftPageEntryCount)
{
splitIndex++;
Debug.Assert(splitIndex < _page.NumberOfEntries);
}
}
DecompressedLeafPage rightDecompressed = null;
int?decompressedPageSize = null;
if (_pageDecompressed != null)
{
decompressedPageSize = _pageDecompressed.PageSize;
}
else if (_splittingOnDecompressed)
{
decompressedPageSize = _page.PageSize;
}
if (decompressedPageSize != null)
{
// splitting the decompressed page, let's allocate the page of the same size to ensure enough space
rightDecompressed = _tx.Environment.DecompressionBuffers.GetPage(_tx, decompressedPageSize.Value, DecompressionUsage.Write, rightPage);
rightPage = rightDecompressed;
}
if (_page.IsLeaf)
{
splitIndex = AdjustSplitPosition(currentIndex, splitIndex, rightPage, ref toRight);
}
Slice currentKey;
using (_page.GetNodeKey(_tx, splitIndex, out currentKey))
{
Slice seperatorKey;
if (toRight && splitIndex == currentIndex)
{
seperatorKey = SliceComparer.Compare(currentKey, _newKey) < 0 ? currentKey : _newKey;
}
else
{
seperatorKey = currentKey;
}
var addedAsImplicitRef = false;
var parentOfPage = _cursor.CurrentPage;
TreePage parentOfRight;
using (rightDecompressed)
{
AddSeparatorToParentPage(rightPage.PageNumber, seperatorKey, out parentOfRight);
if (_page.IsBranch && toRight && SliceComparer.EqualsInline(seperatorKey, _newKey))
{
// _newKey needs to be inserted as first key (BeforeAllKeys) to the right page, so we need to add it before we move entries from the current page
AddNodeToPage(rightPage, 0, Slices.BeforeAllKeys);
addedAsImplicitRef = true;
}
// move the actual entries from page to right page
ushort nKeys = _page.NumberOfEntries;
for (int i = splitIndex; i < nKeys; i++)
{
TreeNodeHeader *node = _page.GetNode(i);
if (_page.IsBranch && rightPage.NumberOfEntries == 0)
{
rightPage.CopyNodeDataToEndOfPage(node, Slices.BeforeAllKeys);
}
else
{
Slice instance;
using (TreeNodeHeader.ToSlicePtr(_tx.Allocator, node, out instance))
{
rightPage.CopyNodeDataToEndOfPage(node, instance);
}
}
}
if (rightDecompressed != null)
{
rightDecompressed.CopyToOriginal(_tx, defragRequired: false, wasModified: true, _tree);
rightPage = rightDecompressed.Original;
}
}
_page.Truncate(_tx, splitIndex);
RecompressPageIfNeeded(wasModified: true);
byte *pos;
if (addedAsImplicitRef == false)
{
try
{
if (toRight && _cursor.CurrentPage.PageNumber != parentOfRight.PageNumber)
{
// modify the cursor if we are going to insert to the right page
_cursor.Pop();
_cursor.Push(parentOfRight);
}
// actually insert the new key
pos = InsertNewKey(toRight ? rightPage : _page);
}
catch (InvalidOperationException e)
{
if (
e.Message.StartsWith("The page is full and cannot add an entry", StringComparison.Ordinal) ==
false)
{
throw;
}
throw new InvalidOperationException(
GatherDetailedDebugInfo(rightPage, currentKey, seperatorKey, currentIndex, splitIndex,
toRight), e);
}
}
else
{
pos = null;
_cursor.Push(rightPage);
}
if (_page.IsBranch)
// remove a branch that has only one entry, the page ref needs to be added to the parent of the current page
{
Debug.Assert(_page.NumberOfEntries > 0);
Debug.Assert(rightPage.NumberOfEntries > 0);
if (_page.NumberOfEntries == 1)
{
RemoveBranchWithOneEntry(_page, parentOfPage);
}
if (rightPage.NumberOfEntries == 1)
{
RemoveBranchWithOneEntry(rightPage, parentOfRight);
}
}
return(pos);
}
}
private Slice GetActualKey(TreePage page, int pos)
{
TreeNodeHeader *_;
return(GetActualKey(page, pos, out _));
}
public void MultiAdd(Slice key, Slice value)
{
if (!value.HasValue)
{
throw new ArgumentNullException(nameof(value));
}
int maxNodeSize = Llt.DataPager.NodeMaxSize;
if (value.Size > maxNodeSize)
{
throw new ArgumentException("Cannot add a value to child tree that is over " + maxNodeSize + " bytes in size", nameof(value));
}
if (value.Size == 0)
{
throw new ArgumentException("Cannot add empty value to child tree");
}
State.IsModified = true;
State.Flags |= TreeFlags.MultiValueTrees;
TreeNodeHeader *node;
var page = FindPageFor(key, out node);
if (page == null || page.LastMatch != 0)
{
MultiAddOnNewValue(key, value, maxNodeSize);
return;
}
page = ModifyPage(page);
var item = page.GetNode(page.LastSearchPosition);
byte *_;
// already was turned into a multi tree, not much to do here
if (item->Flags == TreeNodeFlags.MultiValuePageRef)
{
var existingTree = OpenMultiValueTree(key, item);
existingTree.DirectAdd(value, 0, out _).Dispose();
return;
}
if (item->Flags == TreeNodeFlags.PageRef)
{
throw new InvalidOperationException("Multi trees don't use overflows");
}
var nestedPagePtr = DirectAccessFromHeader(item);
var nestedPage = new TreePage(nestedPagePtr, (ushort)GetDataSize(item));
var existingItem = nestedPage.Search(_llt, value);
if (nestedPage.LastMatch != 0)
{
existingItem = null;// not an actual match, just greater than
}
if (existingItem != null)
{
// maybe same value added twice?
Slice tmpKey;
using (TreeNodeHeader.ToSlicePtr(_llt.Allocator, item, out tmpKey))
{
if (SliceComparer.Equals(tmpKey, value))
{
return; // already there, turning into a no-op
}
}
nestedPage.RemoveNode(nestedPage.LastSearchPosition);
}
if (nestedPage.HasSpaceFor(_llt, value, 0))
{
// we are now working on top of the modified root page, we can just modify the memory directly
nestedPage.AddDataNode(nestedPage.LastSearchPosition, value, 0);
return;
}
if (page.HasSpaceFor(_llt, value, 0))
{
// page has space for an additional node in nested page ...
var requiredSpace = nestedPage.PageSize + // existing page
nestedPage.GetRequiredSpace(value, 0); // new node
if (requiredSpace + Constants.Tree.NodeHeaderSize <= maxNodeSize)
{
// ... and it won't require to create an overflow, so we can just expand the current value, no need to create a nested tree yet
EnsureNestedPagePointer(page, item, ref nestedPage, ref nestedPagePtr);
var newPageSize = (ushort)Math.Min(Bits.NextPowerOf2(requiredSpace), maxNodeSize - Constants.Tree.NodeHeaderSize);
ExpandMultiTreeNestedPageSize(key, value, nestedPagePtr, newPageSize, nestedPage.PageSize);
return;
}
}
EnsureNestedPagePointer(page, item, ref nestedPage, ref nestedPagePtr);
// we now have to convert this into a tree instance, instead of just a nested page
var tree = Create(_llt, _tx, key, TreeFlags.MultiValue);
for (int i = 0; i < nestedPage.NumberOfEntries; i++)
{
Slice existingValue;
using (nestedPage.GetNodeKey(_llt, i, out existingValue))
{
tree.DirectAdd(existingValue, 0, out _).Dispose();
}
}
tree.DirectAdd(value, 0, out _).Dispose();
_tx.AddMultiValueTree(this, key, tree);
// we need to record that we switched to tree mode here, so the next call wouldn't also try to create the tree again
DirectAdd(key, sizeof(TreeRootHeader), TreeNodeFlags.MultiValuePageRef, out _).Dispose();
}
private void EnsureNestedPagePointer(TreePage page, TreeNodeHeader *currentItem, ref TreePage nestedPage, ref byte *nestedPagePtr)
{
var movedItem = page.GetNode(page.LastSearchPosition);
if (movedItem == currentItem)
{
return;
}
// HasSpaceFor could called Defrag internally and read item has moved
// need to ensure the nested page has a valid pointer
nestedPagePtr = DirectAccessFromHeader(movedItem);
nestedPage = new TreePage(nestedPagePtr, (ushort)GetDataSize(movedItem));
}
private void HandleUncompressedNodes(DecompressedLeafPage decompressedPage, TreePage p, DecompressionUsage usage)
{
int numberOfEntries = p.NumberOfEntries;
for (var i = 0; i < numberOfEntries; i++)
{
var uncompressedNode = p.GetNode(i);
Slice nodeKey;
using (TreeNodeHeader.ToSlicePtr(_tx.Allocator, uncompressedNode, out nodeKey))
{
if (uncompressedNode->Flags == TreeNodeFlags.CompressionTombstone)
{
HandleTombstone(decompressedPage, nodeKey, usage);
continue;
}
if (decompressedPage.HasSpaceFor(_llt, TreeSizeOf.NodeEntry(uncompressedNode)) == false)
{
throw new InvalidOperationException("Could not add uncompressed node to decompressed page");
}
int index;
if (decompressedPage.NumberOfEntries > 0)
{
Slice lastKey;
using (decompressedPage.GetNodeKey(_llt, decompressedPage.NumberOfEntries - 1, out lastKey))
{
// optimization: it's very likely that uncompressed nodes have greater keys than compressed ones
// when we insert sequential keys
var cmp = SliceComparer.CompareInline(nodeKey, lastKey);
if (cmp > 0)
{
index = decompressedPage.NumberOfEntries;
}
else
{
if (cmp == 0)
{
// update of the last entry, just decrement NumberOfEntries in the page and
// put it at the last position
index = decompressedPage.NumberOfEntries - 1;
decompressedPage.Lower -= Constants.Tree.NodeOffsetSize;
}
else
{
index = decompressedPage.NodePositionFor(_llt, nodeKey);
if (decompressedPage.LastMatch == 0) // update
{
decompressedPage.RemoveNode(index);
if (usage == DecompressionUsage.Write)
{
State.NumberOfEntries--;
}
}
}
}
}
}
else
{
// all uncompressed nodes were compresion tombstones which deleted all entries from the decompressed page
index = 0;
}
switch (uncompressedNode->Flags)
{
case TreeNodeFlags.PageRef:
decompressedPage.AddPageRefNode(index, nodeKey, uncompressedNode->PageNumber);
break;
case TreeNodeFlags.Data:
var pos = decompressedPage.AddDataNode(index, nodeKey, uncompressedNode->DataSize);
var nodeValue = TreeNodeHeader.Reader(_llt, uncompressedNode);
Memory.Copy(pos, nodeValue.Base, nodeValue.Length);
break;
case TreeNodeFlags.MultiValuePageRef:
throw new NotSupportedException("Multi trees do not support compression");
default:
throw new NotSupportedException("Invalid node type to copye: " + uncompressedNode->Flags);
}
}
}
}
public void MultiDelete(Slice key, Slice value)
{
State.IsModified = true;
TreeNodeHeader *node;
var page = FindPageFor(key, out node);
if (page == null || page.LastMatch != 0)
{
return; //nothing to delete - key not found
}
page = ModifyPage(page);
var item = page.GetNode(page.LastSearchPosition);
if (item->Flags == TreeNodeFlags.MultiValuePageRef) //multi-value tree exists
{
var tree = OpenMultiValueTree(key, item);
tree.Delete(value);
// previously, we would convert back to a simple model if we dropped to a single entry
// however, it doesn't really make sense, once you got enough values to go to an actual nested
// tree, you are probably going to remain that way, or be removed completely.
if (tree.State.NumberOfEntries != 0)
{
return;
}
_tx.TryRemoveMultiValueTree(this, key);
if (_newPageAllocator != null)
{
if (IsIndexTree == false)
{
ThrowAttemptToFreePageToNewPageAllocator(Name, tree.State.RootPageNumber);
}
_newPageAllocator.FreePage(tree.State.RootPageNumber);
}
else
{
if (IsIndexTree)
{
ThrowAttemptToFreeIndexPageToFreeSpaceHandling(Name, tree.State.RootPageNumber);
}
_llt.FreePage(tree.State.RootPageNumber);
}
Delete(key);
}
else // we use a nested page here
{
var nestedPage = new TreePage(DirectAccessFromHeader(item), (ushort)GetDataSize(item));
nestedPage.Search(_llt, value); // need to search the value in the nested page
if (nestedPage.LastMatch != 0) // value not found
{
return;
}
if (item->Flags == TreeNodeFlags.PageRef)
{
throw new InvalidOperationException("Multi trees don't use overflows");
}
var nestedPagePtr = DirectAccessFromHeader(item);
nestedPage = new TreePage(nestedPagePtr, (ushort)GetDataSize(item))
{
LastSearchPosition = nestedPage.LastSearchPosition
};
nestedPage.RemoveNode(nestedPage.LastSearchPosition);
if (nestedPage.NumberOfEntries == 0)
{
Delete(key);
}
}
}
private ActualKeyScope GetActualKey(TreePage page, int pos, out TreeNodeHeader *node, out Slice key)
{
DecompressedLeafPage decompressedLeafPage = null;
node = page.GetNode(pos);
var scope = TreeNodeHeader.ToSlicePtr(_tx.Allocator, node, out key);
while (key.Size == 0)
{
Debug.Assert(page.IsBranch);
page = _tree.GetReadOnlyTreePage(node->PageNumber);
if (page.IsCompressed == false)
{
node = page.GetNode(0);
}
else
{
decompressedLeafPage?.Dispose();
decompressedLeafPage = _tree.DecompressPage(page, skipCache: true);
if (decompressedLeafPage.NumberOfEntries > 0)
{
if (page.NumberOfEntries == 0)
{
node = decompressedLeafPage.GetNode(0);
}
else
{
// we want to find the smallest key in compressed page
// it can be inside compressed part or not compressed one
// in particular, it can be the key of compression tombstone node that we don't see after decompression
// so we need to take first keys from decompressed and compressed page and compare them
var decompressedNode = decompressedLeafPage.GetNode(0);
var compressedNode = page.GetNode(0);
using (TreeNodeHeader.ToSlicePtr(_tx.Allocator, decompressedNode, out var firstDecompressedKey))
using (TreeNodeHeader.ToSlicePtr(_tx.Allocator, compressedNode, out var firstCompressedKey))
{
node = SliceComparer.CompareInline(firstDecompressedKey, firstCompressedKey) > 0 ? compressedNode : decompressedNode;
}
}
}
else
{
// we have empty page after decompression (each compressed entry has a corresponding CompressionTombstone)
// we can safely use the node key of first tombstone (they have proper order)
node = page.GetNode(0);
}
}
scope.Dispose();
scope = TreeNodeHeader.ToSlicePtr(_tx.Allocator, node, out key);
}
return(new ActualKeyScope
{
DecompressedLeafPage = decompressedLeafPage,
ExternalScope = scope
});
}
public byte *Execute()
{
using (DisableFreeSpaceUsageIfSplittingRootTree())
{
if (_page.IsLeaf)
{
_tree.ClearPagesCache();
}
if (_page.IsCompressed)
{
_pageDecompressed = _tree.DecompressPage(_page, WriteDecompressionUsage, skipCache: false);
_pageDecompressed.Search(_tx, _newKey);
if (_pageDecompressed.LastMatch == 0)
{
// we are going to insert the value in a bit, but it might have
// been in the compressed portion and not removed by the calling
// code
_tree.RemoveLeafNode(_pageDecompressed);
if (_pageDecompressed.NumberOfEntries == 0)
{
// we have just removed the last node that we wanted to update
// there is no need to do any split - copy the value to the current (empty) page
using (_pageDecompressed)
{
RecompressPageIfNeeded(wasModified: true);
var pos = InsertNewKey(_page);
return(pos);
}
}
}
_page = _pageDecompressed;
}
TreePage rightPage = _tree.NewPage(_page.TreeFlags, _page.PageNumber);
if (_cursor.PageCount == 0) // we need to do a root split
{
TreePage newRootPage = _tree.NewPage(TreePageFlags.Branch, _page.PageNumber);
_cursor.Push(newRootPage);
_tree.State.RootPageNumber = newRootPage.PageNumber;
_tree.State.Depth++;
// now add implicit left page
newRootPage.AddPageRefNode(0, Slices.BeforeAllKeys, _page.PageNumber);
_parentPage = newRootPage;
_parentPage.LastSearchPosition++;
}
else
{
// we already popped the page, so the current one on the stack is the parent of the page
_parentPage = _tree.ModifyPage(_cursor.CurrentPage);
_cursor.Update(_cursor.Pages, _parentPage);
}
using (_pageDecompressed)
{
if (_page.LastSearchPosition >= _page.NumberOfEntries)
{
var pos = OptimizedOnlyMoveNewValueToTheRightPage(rightPage);
RecompressPageIfNeeded(wasModified: false);
return(pos);
}
return(SplitPageInHalf(rightPage));
}
}
}
private byte *AddSeparatorToParentPage(long pageRefNumber, Slice separatorKey, out TreePage parentOfPageRef)
{
var parent = new ParentPageAction(_parentPage, _page, _tree, _cursor, _tx);
var pos = parent.AddSeparator(separatorKey, pageRefNumber);
parentOfPageRef = parent.ParentOfAddedPageRef;
return(pos);
}
public TreePage Execute(TreePage page)
{
using (DisableFreeSpaceUsageIfSplittingRootTree())
{
_tree.ClearPagesCache();
if (_cursor.PageCount <= 1) // the root page
{
RebalanceRoot(page);
return(null);
}
_cursor.Pop();
var parentPage = _tree.ModifyPage(_cursor.CurrentPage);
_cursor.Update(_cursor.Pages, parentPage);
if (page.NumberOfEntries == 0) // empty page, just delete it and fixup parent
{
// need to change the implicit left page
if (parentPage.LastSearchPosition == 0 && parentPage.NumberOfEntries > 2)
{
var newImplicit = parentPage.GetNode(1)->PageNumber;
parentPage.RemoveNode(0);
parentPage.ChangeImplicitRefPageNode(newImplicit);
}
else // will be set to rights by the next rebalance call
{
parentPage.RemoveNode(parentPage.LastSearchPositionOrLastEntry);
}
_tree.FreePage(page);
return(parentPage);
}
if (page.IsBranch && page.NumberOfEntries == 1)
{
RemoveBranchWithOneEntry(page, parentPage);
return(parentPage);
}
var minKeys = page.IsBranch ? 2 : 1;
if ((page.UseMoreSizeThan(_tx.DataPager.PageMinSpace)) && page.NumberOfEntries >= minKeys)
{
return(null); // above space/keys thresholds
}
Debug.Assert(parentPage.NumberOfEntries >= 2); // if we have less than 2 entries in the parent, the tree is invalid
var sibling = SetupMoveOrMerge(page, parentPage);
Debug.Assert(sibling.PageNumber != page.PageNumber);
if (page.TreeFlags != sibling.TreeFlags)
{
return(null);
}
if (sibling.IsCompressed)
{
return(null);
}
if (sibling.PageSize != page.PageSize)
{
// if the current page is compressed (but already opened), we need to
// avoid merging it with the right (uncompressed) page
return(null);
}
Debug.Assert(page.IsCompressed == false);
minKeys = sibling.IsBranch ? 2 : 1; // branch must have at least 2 keys
if (sibling.UseMoreSizeThan(_tx.DataPager.PageMinSpace) &&
sibling.NumberOfEntries > minKeys)
{
// neighbor is over the min size and has enough key, can move just one key to the current page
if (page.IsBranch)
{
MoveBranchNode(parentPage, sibling, page);
}
else
{
MoveLeafNode(parentPage, sibling, page);
}
return(parentPage);
}
if (page.LastSearchPosition == 0) // this is the right page, merge left
{
if (TryMergePages(parentPage, sibling, page) == false)
{
return(null);
}
}
else // this is the left page, merge right
{
if (TryMergePages(parentPage, page, sibling) == false)
{
return(null);
}
}
return(parentPage);
}
}
private void MoveLeafNode(TreePage parentPage, TreePage from, TreePage to)
{
Debug.Assert(from.IsBranch == false);
var originalFromKeyStart = GetActualKey(from, from.LastSearchPositionOrLastEntry);
var fromNode = from.GetNode(from.LastSearchPosition);
byte *val = @from.Base + @from.KeysOffsets[@from.LastSearchPosition] + Constants.NodeHeaderSize + originalFromKeyStart.Size;
var nodeVersion = fromNode->Version; // every time new node is allocated the version is increased, but in this case we do not want to increase it
if (nodeVersion > 0)
{
nodeVersion -= 1;
}
byte *dataPos;
var fromDataSize = fromNode->DataSize;
switch (fromNode->Flags)
{
case TreeNodeFlags.PageRef:
to.EnsureHasSpaceFor(_tx, originalFromKeyStart, -1);
dataPos = to.AddPageRefNode(to.LastSearchPosition, originalFromKeyStart, fromNode->PageNumber);
break;
case TreeNodeFlags.Data:
to.EnsureHasSpaceFor(_tx, originalFromKeyStart, fromDataSize);
dataPos = to.AddDataNode(to.LastSearchPosition, originalFromKeyStart, fromDataSize, nodeVersion);
break;
case TreeNodeFlags.MultiValuePageRef:
to.EnsureHasSpaceFor(_tx, originalFromKeyStart, fromDataSize);
dataPos = to.AddMultiValueNode(to.LastSearchPosition, originalFromKeyStart, fromDataSize, nodeVersion);
break;
default:
throw new NotSupportedException("Invalid node type to move: " + fromNode->Flags);
}
if (dataPos != null && fromDataSize > 0)
{
Memory.Copy(dataPos, val, fromDataSize);
}
from.RemoveNode(from.LastSearchPositionOrLastEntry);
var pos = parentPage.LastSearchPositionOrLastEntry;
parentPage.RemoveNode(pos);
var newSeparatorKey = GetActualKey(to, 0); // get the next smallest key it has now
var pageNumber = to.PageNumber;
if (parentPage.GetNode(0)->PageNumber == to.PageNumber)
{
pageNumber = from.PageNumber;
newSeparatorKey = GetActualKey(from, 0);
}
AddSeparatorToParentPage(to, parentPage, pageNumber, newSeparatorKey, pos);
}
private ActualKeyScope GetActualKey(TreePage page, int pos, out Slice slice)
{
TreeNodeHeader *_;
return(GetActualKey(page, pos, out _, out slice));
}
private static void ThrowOnCompressedPage(TreePage p)
{
throw new InvalidOperationException($"Page {p.PageNumber} is compressed. You need to decompress it to be able to access its content.");
}